Us humans may focus on our five senses when we think about how the world around us can be explored and known more fully. But what we can sense is just a small slice of what is really out there. Things get way more exotic when we look at the unusual senses that many types of animals have. Pit vipers, for instance, can see heat with infrared sensors that sit just below their nostrils. Certain sharks and rays can sense electric fields, which gives them a sort of low-light vision. And then there are bats, which use echolocation to navigate and find food.
That is just the tip of the iceberg when it comes to odd sensing mechanisms in nature. We may be missing out on them, but by studying these mechanisms we can build artificial systems that provide us with very similar information. A team led by researchers at the University of Antwerp has recently created an innovative system that will help us to further understand the echolocation mechanisms of bats and other creatures. It is hoped that the insights gleaned through the use of this system will help us to develop new sensing technologies in the future.
Unlocking the secrets of echolocation
The device consists of a 3D sonar system that, when combined with high-speed cameras, allows scientists to visualize echolocation at a level of detail that was previously not possible. This system, known as the Flutter Real-Time Imaging Sonar (FL-RTIS), was designed to investigate many intriguing natural phenomena. It could unlock the secrets behind how bats use echoes to track and capture prey, and how certain insects protect themselves with countermeasures like sound-absorbing scales, for example.
Unlike previous technologies, which either required minutes to compile a full 3D sound scan or could only capture sound from a single direction, FL-RTIS can rapidly track the echoes of moving insects in 3D at a rate of 100 hertz. This is significant because it mirrors the “terminal buzz phase” of bat echolocation — the rapid bursts of sound that bats use when closing in on prey.
How the FL-RTIS system works
The system contains an array of microphones, a broadband ultrasonic speaker, and an embedded GPU for real-time processing. A technique called minimum variance distortionless response beamforming enhances target detection and suppresses background noise, making it possible to isolate and analyze precise echolocation signals. Synchronization between the high-speed camera and 3D sonar system is achieved using a blinking LED light and a random electrical signal, ensuring that the two data streams align with microsecond precision. The final result is a video stream with a graphical representation of echolocation signals overlaid on top.
Initial tests of FL-RTIS included controlled experiments in the lab with rotating fans and fluttering insects, followed by field tests in Ecuador and Mozambique. The system successfully recorded echoes from around 200 insect specimens, capturing valuable data that is now being analyzed. Early results suggest that FL-RTIS will be able to provide deeper insights into predator-prey interactions, as was hoped by the researchers.
Beyond its immediate applications in studying bats and insects, this technology could inspire the development of advanced sonar and radar systems. Potential future applications include improved assistive devices for the visually impaired, enhanced drone navigation systems, and even more effective biomedical imaging techniques.
